Method of separating hydrogen from hydrogen containing gases



Oct. 17, 1950 A. B. wELTY, JR 2,526,524

METHOD 0F SEPARATING HYDROGEN FROM HYDROGEN CONTAINING GASES Filed Dec.14, 1944 se w oD n' a 3 5 Y I 2 o 9 9 lo i 2 o g Id I; 3 *z- G 0 U l 0E' V1 f5 z O J i5 r l? d Q f3 E g A d d va l l f m r Q o Q O' Lv m l l eO l f` N f l o Q 'z1D *f' 3 0 l!) d2 E 0 0 aA m lll :rp m

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V METHOD OF. SEPARATING HYDROGEN FROM HYROGEN CONTAINI-NG GASES AlbertB.We1ty; Jr., Mountainsiae, VN. J., assigner to StandardOileveopmentCompany; acorporationof Delaware Application December 14,1944, Vserial Ne. 568,126n

2` Claims: (Cl. 23e-210) The present' invention 'relates Vto purifying'h'y' drogen'or' to obtaining hydrogen from a mixture oflgases'containing the' samein' 'a richer or more" concentrated statethan in the original mixture;

In the petroleumindustry as Well as in certain others, normally gaseoushydrocarbons' are obtainedas a by-pro'duct This liydro'carb'ongas oftencontains appreciable quantites'of hydrogen which, if recoveredinrelatively` purey form, could be'usedl advantageously in otherprocesses such as hydroge'na'tiori"of` hydrocarbons, arri moni'asyntheses, etc. Sources of such hydrogen` containing gas are' catalyticcracking; buten'e 'dee hydrogenation, hydroformingf thermal cracking,butane dehydrog'enation, and other'petrol'euni refinery processes. Thehydrogen' maybe present in' concentrations'as" lovvv as 10L2O per centVby volume'or as high as 80L90 p'er cent1' The present inventioncomprisesa process for recoveri'rig'this hydrogen in` a more' concentrated"t andlusable f'r1'f1`.`

The main object of" thepresentJ invention thereforefis to recover'th'e'hydrogen in anon-'- centrated-form from' a" source"irrwhich"it'y ismixed" and/or' diluted vvitlrother gases; such as normallygaseous'hydrocarbons;

Anothefobject'of thepre's'en't invention is td' recover hydrogen gas inconcentratedforn'i" from:A a'mixture of 'hydrogen and othergase's in' acontinuous' operation'an'd in a manner which cheaper and more'expeditious' than the' methods' previously" employed.`

Other and' furtherobjects `Aor' the present irr-` vention will appearfrom'th'e followingrnore del ta'iled" description' and' claims 'In' the'accompanying drawing I have Vshown' diagrammatically a"` formA andarrangement oi' apparatus elements in whichapreferred' modication. ofmy'in'vention maybe'carriedinto effect'.

In the drawings similar'reference characters" referto similar parts.Referring in'detailto the drawing, I provide' tivo' cylindrical' cases`I and 2 provided with conical basesv and a reticul'ated member R'Whichmay be a screen or grid. AS will presently appear; the gist of thepresent in'- vention 'resides' in causing' a hydrogenecontain'- ing gasto contact, at elevatedv temperatures,Y asolid,A adsorbentl material'which selectively adsorbs hydrogen', and thereafter, in a separate-Zone; to treat thefad'sorbent materialwith a con-Y f densable gas todisplace the hydrogen, and' to formfazmixtureoihydrogeri andicondensablegas, which; condensablegas .-mayfbe'i li'que'ed andlse'parate'd frontth'ehydrogen; thus@providinghydror ,geniin aconcentrat'edorenriched'l-fo'rmi l Toward this' end', therefore, thehydrogen-containing gas enters the systemftlir'ough line' I0, is mixedwith a `powdered solid material discharged 'into line l0 fromiastandpipe I2` controlled by valve I4 to form asuspensionof the solidmaterial in gas,

Which suspension' is th'erconveyed to theV ,bote tom of treater I Whereit passes upwardly through grid Rto' forin above the grid to the levelL, 'a dense suspension o'f'solid in gas, caused' that theVsolid'fadsorbent'material is'molybdenum oxide (12"W`eight'per cent)carried on activated alumina (w'eight'perc'en't) and' that thisadsorbent" is iIi the form of a powder having a particle'size of from3D0-400 mesh, by controlling the linear velocity of the gasesin theadsorption Zone I 'within the vlimits of M1 to 5 ft. per second,preferably 1/2 to 3' ft. per second, and supplyingA suicient adsorbentso that the dense suspension existingbetween R and L weighs from 15 to25 lbs. per cubic' foot, then the said dense suspension is obtained.' Itis important to note that the standpipev I2 is' in' communication withcase 2, which latter case is at a point elevated above adsorption zone Ilso'tlat a natural'oW of solid adsorbentmaterial from' zone 2 to zone Imay be effected by the static pressure'developed by the elevatedposition 'of case 2; To aid in this free flow, and particularly toprevent bridging and plugging in' standpipe I2`, I provide a number oftaps I5 in communication with standpipe I2, through which taps I forceinto the said standpipe, a slow current of gas, such as some of the gasin line IU; in order to maintain thedownowing powdered'material actuallyfed to adsorption zone I is controlled by valve ifi, and by controllingthe flow ofmaterial, that is, the amount of powdered material fed toadsorption zone I, andthe linear velocity of the gasiform materialthereirrjl may'x'theupper level L, of the dense suspension previouslyreferred to.

Above Lthere isa space S in which a suspension of catalyst in gasis verysubstantially less thanrbelow L. Hence, as the gas exits fromadsorption'zone I through line 2@ the concen-` tration of powderedmaterial may be as low as This gas may be passed throughsolid-gasseparating devicessuch 0.03() -lb. per cubicA foot.

as centrifugal separators, electrical precipitators, and the like, toseparate the last tracesof ad# sorbent material.' I have omitted ashowing of conventional apparatus so as to' direct attention' to thereal heart ofthe present invention, Alsoit is desirable to include aplurality of centrifugal separators (not shown) within case I in thespace S to cause the separation of solid from gas by passage of thesuspension therethrough, or to employ any known gas-solid contactingdevices for effecting the above stated solid separation from gas.

Up to this point it will be observed I have described the method offeeding adsorbent material to an adsorption zone, together with ahydrogencontaining gas. My purpose is to adsorb and thereby remove fromthe hydrogen-containing gas, hydrogen, and to procure it in an adsorbedform on or within the powdered material so that the gas issuing throughline l2Ii will be depleted in hydrogen content. I have found thattemperatures of from (i90-200W F. but preferably from 900-1400" F. givebest results,` The pressure in the adsorption zone may be approximatelyatmospheric. The amount of adsorbent material charged to adsorption zoneI with the gas Varies with the nature of the adsorbent, but in the caseof molybdenum oxide on alumina, which I have mentioned, I nd that goodresults are obtained by charging 3-30 lbs. of catalyst per cubic foot ofhydrogen-containing gas, measured at standard conditions. Y Y

The adsorbent material containing the adsorbed hydrogen is continuouslywithdrawn from adsorption zone I through a second standpipe 3D alsoprovided with suitable taps 3I into which gas may be bled to preventplugging and bridging within the standpipe, and also carrying a flowcontrol valve 32. The lower end of standpipe 3U is in communication witha steam line 35 and the adsorbent material is discharged into said line35 after which it is carried in the steam into the bottom of thestripping zone 2. The flow of steam and quantity of adsorbent materialin stripping zone 2 is maintained under the same conditions as existingin adsorption zone I, that is to say, the velocity of the gas and/ orvapor is maintained within the limits of from 1/4 to 5 ft. per second,and catalyst is fed to zone 2 at such a rate as to keep the level L inzone 2 at the desired height. The density of this iiuidized mass in zone2 is from 5-50 lbs. per cubic foot. The steam in line 35 is superheatedto say 1000 to 1400" F. for best results.

The steam serves to purge out or displace the hydrogen adsorbed by theadsorbent material, and a mixture of steam and hydrogen passes from thestripping zone 5 through line 49. AS in the case of line 20, theconcentration of adsorbent material in gas is very low, but neverthelessit contains suilcient solid entrained material to make it necessary topass the mixture through gas-solid contacting devices which will removethe last tracesof solid material, such as centrifugal" separators 56.Two or more of these separators may be employed, and also one or moreelectrical precipitators, if necessary, to separate the adsorbentmaterial from the steam and hydrogen.

The said hydrogen and steam in line 60 passes through a condenser 'I0where it is cooled sufciently to condense the steam, and then themixture of condensate and hydrogen is discharged into a separator l5from which the hydrogencontaining gas may be recovered through line 75.

Instead of employing molybdenum oxide on alumina, which I have found iscapable of adsorbing at least 7-8 volumes of hydrogen per volume ofcatalyst, I may use other adsorbent materials, The molybdenum oxide maybe used supported on suitable material, such as an acid treatedBentonitic clay, activated alumina, pumice, Attapulgus clay, silica gel,silica-alumina gel and the like. A particular suitable adsorbent ismoiybdena on alumina, as previously mentioned.

To recapitulate, the present invention is concerned With obtaining froma hydrogen-containing gas a quantity of hydrogen-containing gas richerin hydrogen than the rst mentioned gas. I accomplish this result bycontacting the original hydrogen-containing gas with a solid adsorbentpowdered material in the form of a turbulent, iiuidized mass of powderedadsorbent material carried in dense suspension in a gas in an adsorptionZone, removing the adsorbent material containing adsorbed hydrogen andconducting it to a steam stripping zone where it is contacted with steamin the form of a turbulent iluidized mass of powdered material carriedin dense suspension in said steam whereby the steam serves to striphydrogen from the adsorbent to provide a gaseous mixture containingsteam and hydrogen, which mixture may be cooled to condense the waterand to provide a hydrogen-enriched gas.

Without wishing to be bound by any theory of operation, I believe thatmy'process operates as follows: The solid adsorbent material in adsorp`tion Zone I, that is the supported molybdenum oxide, preferentiallyadsorbs the hydrogen from the hydrogen-rich stream. At the same time theadsorbent will be reduced somewhat. In the stripping zone the steam willbe preferentially adsorbed thus desorbing the hydrogen from the surface.At least partial reoxidation also may occur, thus contributing to thehydrogen release. In the case of M003 on alumina about of the hydrogenobtained was adsorbed on the surface of the solid at l000 F. and latmosphere pressure.

My process is distinguishable over the art on the steam-iron process formaking hydrogen, for example, in two particulars as follows: (l) Thetemperatures employed in Zone I of my process are lower; and (2) in thesteam-iron process no appreciable amount of hydrogen is adsorbed. It ispossible to obtain commercially pure hydrogen by my process from gasescontaining a minor proportion of hydrogen.

' There will come a time when the solid ad sorbent material may becomefouled with carbonaceous material due to the fact that it is in contactwith hydrocarbons and, in particular, olefins at relatively hightemperatures, and in that case it will be necessary to remove a streamof the material in line I2 to a third uidizing zone (not shown) where itis contacted with air for the purpose of burning off contaminants andpurifying the adsorbent material. This third uidizing zone may be of thesame shape and size as zones I and 2 and may be operated in like mannerusing, of course, an oxygen-containing gas instead of ahydrogen-containing gas. I deem it unnecessary to illustrate thisfeature of my invention for others have disclosed methods forregenerating by burning powdered adsorbent material while it is in theform of a dense suspension in a regeneration gas.

Numerous modications of my invention will suggest themsevles to thosewho are familiar with this art without departing from the spiritthereof.

What I claim-is:

1. A continuous method for recovering hydrogen from a gaseous mixtureconsisting of hydrogen and normally gaseous hydrocarbons whichcomprises: charging the said gaseous mixture to withdrawn solidparticles with steam, and c0n,

ducting the suspension to a stripping zone Where it is formed into aturbulent uidized mass of solid particles carried in dense suspension insteam, whereby the steam serves to displace adsorbed hydrogen from thesolid particles, withdrawing a gaseous stream from the stripping zoneconsisting of steam and hydrogen, cooling the said gaseous stream tocondense the steam, and thereafter recovering hydrogen from thecondensed steam.

2. The method of claim 1 in which the said adsorptive carrier consistsof about 12 weight percent of molybdenum oxide and 88 weight per- 6 centactivated alumina and in which the said solid particles have a particlesize smaller than about 100 mesh.

ALBERT B. W'ELTY, J R..

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,198,560 Marshall Apr. 23, 19402,361,978 Swearingen Nov. 7, 1944 FOREIGN PATENTS Number Country Date4,134 Great Britain Aug. 22, 1891 10,356 Great Britain May '7, 1903OTT-IEBl REFERENCES Mellor, Comprehensive Treatise on Inorganic andTheoretical Chemistry, vol I, p. 280, VOLXI, pp. 513, 540.

Lange, Handbook of Chemistry, 5th edition, pp. 762-763.

1. A CONTINUOUS METHOD FOR RECOVERING HYDROGEN FROM A GASEOUS MIXTURECONSISTING OF HYDROGEN AND NORMALLY GASEOUS HYDROCARBONS WHICHCOMPRISES: CHARGING THE SAID GASEOUS MIXTURE TO AN ADSORPTION ZONECONTAINING A TURBULENT FLUIDIZED MASS OF SOLID PARTICLES CONSISTING OFMOLYBDENUM OXIDE SUPPORTED ON ACTIVATED ALUMINA, PERMITTING THE HYDROGENCONTAINING AS TO CONTACT THE SOLID PARTICLES IN THE ADSORPTION ZONE AT ATEMPERATURE WITHIN THE RANGE OF ABOUT 900 TO 1400*F. AND AT A PRESSUREOF ABOUT ONE ATMOSPHERE, WHEREBY AT LEAST A PORTION OF THE HYDROGEN INTHE GASEOUS MIXTURE IS ABSORBED BY THE SAID SOLID PARTICLES, WITHDRAWINGCONTINUOUSLY FROM THE ADSORPTION ZONE SOLID PARTICLES INCLUDING ADSORBEDHYDROGEN, FORMING A SUSPENSION OF SAID WITHDRAWN SOLID PARTICLES WITHSTEAM, AND CONDUCTING THE SUSPENSION TO A STRIPPING ZONE WHERE IT ISFORMED INTO A TURBULENT FLUIDIZED MASS OF SOLID PARTICLES CARRIED DENSESUSPENSION IN